I don't have that camera but have a Canon A75 and Canon Rebel XT, so I'd imagine it would also have a Manual mode. If that's the case, try playing around in that mode instead of using the sports setting.

It's likely your ISO is set to a higher number. If you were to use ISO 100 instead of ISO 400, your pictures would be less grainier but also darker. To make up for the darkness, you will have to lower your shutter speed and pick a lower aperture number (for example, F/2.8 instead of F/8). You can only lower your shutter speed so much before everything is a blur, however. And there's only so many choices for apertures. If things are still dark, you *may* have to bump up the ISO to something like 200 but but that's a heck of a lot better than 400.

You can also use flash so that you can lower your ISO without having to worry about playing around with the other settings.